We explore the thermalization of energetic partons in quark-gluon plasma medium by analyzing the medium response effect on jet substructure observables. In high-energy heavy-ion collisions, jets become more populated by soft partons through the induced radiation and scatterings in the medium. Consequently, the energies of some soft jet partons reach the typical energy of the medium...
Quarks and gluons traversing a QCD medium may lose energy through a variety of processes, including medium-induced radiation sensitive to their QCD color factor.
The color-charge dependence of the parton-medium interaction is a critical component in all jet energy loss models and generally in heavy-ion physics phenomenology. In this talk, the color charge dependence of jet-medium...
Measuring the jet substructure in heavy-ion collisions provides exciting new opportunities to study detailed aspects of the dynamics of jet quenching in the hot and dense QCD medium created
in these collisions. In this talk, we present new ATLAS measurements of jet substructure performed using various jet (de)clustering and grooming techniques. Measurements of inclusive jet suppression...
The Quark-Gluon Plasma, a state of matter characterized by its extreme energy density and temperature generated in heavy-ion collision experiments, is expected to modify hard-scattered partons traveling through it and, consequently, the jets they produce. Analyses regarding jets may recover information about the medium and its partonic energy-loss mechanism. This work applies the Monte Carlo...
We revisit the picture of jets propagating in the quark-gluon plasma. In addition to vacuum radiation, related to the high initial virtuality of a jet, jet particles scatter on the medium constituents resulting in induced emissions. Analytical approaches to resumming these interactions have traditionally dealt separately with multiple, soft [1,2], or rare, hard scatterings [3,4]. A full...
Jet modification is a multi-stage (multi-scale) process: an initial high virtuality stage gives way to a lower virtuality transport stage for high energy partons, and a strongly coupled phase for lower energy parts of the shower. The transition from the high virtuality medium-modified DGLAP stage takes place when the virtuality reaches the medium induced scale 𝑞̂ 𝜏, where 𝜏 is the lifetime of...
Ultra-relativistic collisions of small nuclear systems can shed light on the onset of QGP formation. So far, proton-nucleus (p+A) and deuteron-nucleus (d+A) collisions have been used to study the emergence of the smallest QGP droplets, producing the puzzling results that the non-zero elliptic flow of hadrons at intermediate transverse momenta is not correlated to the suppression of their...
Central and mid-peripheral heavy-ion collisions produce a significant underlying event superimposed on the hard scattering of interest. So far, traditional underlying event mitigation algorithms introduced for heavy-ion often impose limitations in their applicability. The jet typically has to be clustered in the presence of the underlying event. Observables like the energy have to be corrected...
The selection of jets in heavy-ion collisions based on their quenched $p_T$ is known to bias towards jets that lost little energy. We illustrate this explicitly in a simplified Monte Carlo study in which it is possible to identify the same jet before and after quenching. We find that selecting a sample of jets based on their quenched $p_T$ yields a sample of jets whose fractional energy loss...
We study nonperturbative flavor correlations between pairs of leading and next- to-leading charged hadrons within jets and their modifications in the presence of a QCD medium. A charge correlation ratio observable $r_{c}$, generalized from the balance function [1] which distinguishes between same-sign and opposite-sign charged pairs, is introduced. This observable $r_c$ is studied as a...
The sPHENIX detector at the Relativistic Heavy Ion Collider is designed to measure high momentum probes of the quark-gluon plasma such as jets. Jet measurements in heavy-ion collisions require subtraction of the large underlying event consisting of low momentum particles produced from the QGP medium. While subtraction techniques can remove the average size of the background, localized...
Experimental data on a wide range of jet observables measured in heavy-ion collisions provide strong constraints on the underlying medium dynamics and are addressed by state-of-the-art Monte Carlo models. However, so far there has been little theoretical guidance on the systematics of medium modifications on such diverse quantities as the inclusive jet spectrum, the intra-jet fragmentation...
We study jet momentum broadening in heavy ion collisions at initial stages. We focus on the jet quenching parameter $\hat q$, which we extract using effective kinetic theory. We obtain its non-equilibrium properties during the initial stages in a Bjorken-expanding plasma with non-thermal anisotropic initial conditions.
I will discuss recent work that aims to understand the initial state of the fragmentation region of heavy ion collisions using an entirely classical framework that incorporates the phenomenon of gluon saturation. The first step in the program, recently carried out by Kajantie, McLerran, and Paatelainen, is to study the gluon radiation from a classical point particle struck by a sheet of...
